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Somebody in the thread at some point said:
| Andy Green wrote:
|> It could be that chgena = 0 means no system power but it seems a bit
|> insane (especially as chgena is 0 from the get-go as we now know).
|| I does, indeed. I poked around some more, and the PMU is sane when it
| comes to that. However, I'm not sure you'll like all my results ...
Not at all, I didn't see anything I didn't like worse than the disproved
"charger disable depowers whole device" thing. Nice work examining it all.
| Observations:
| - the USB-SYS path works as documented
| - the charger does not need to be enabled for USB-SYS to work
| - system runs from battery alone, USB alone, and both combined
Good this is what I experienced too, and its compatible with --->
| - if there is no battery and we try to enable the charger, the
| system turns off instantly (!!!)
... because back in the day when I was running fine with no battery, I
am not sure charging in U-Boot was straightened out.
| We also draw more than 100mA even before reaching the wait_for_power
| loop (and there, blinking the LED makes things even worse, but this
| is expected). So we need to save a bit of power in the early system
| bringup.
We could crank up the clock later I suppose, keeping the backlight, LCM
and Glamo all down if they're up at this time. The Glamo has 80MHz PLL
and its own DRAM so I don't think it's that cheap to run. The other
assets on the device are meant to be down by default already AFAIK.
| There's also the mystery result that enabling the charger while running
| only from battery reduces battery current. That must be some of that
| Dark Energy everybody's talking about.
This doesn't violate any laws of physics, the universe has taken care
that you cannot actually charge a battery with it since it only comes
when you disable the charger ;-)
- -Andy
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